Apparatus for raising and lowering cover plates



May 6, 1969 D. D. SNAVELY 3,442,399

APPARATUS FOR RAISING AND LOWERING COVER PLATES I Filed Oct. 28, 1966 ow/vroe DONALD 0. SNAVELY Bx/ojdn'y United States Patent 3,442,399APPARATUS FOR RAISING AND LOWERING COVER PLATES Donald D. Snavely,Atlanta, Ga., assignor to H. H.

Robertson Company, Pittsburgh, Pa., a corporation of Pennsylvania FiledOct. 28, 1966, Ser. No. 590,272 Int. Cl. B66c 1/42 US. Cl. 214-1 7Claims ABSTRACT OF THE DISCLOSURE A portable device for removing andreplacing a metal cover plate of an electrical trench. The deviceincludes ground engaging elements positioned to straddle the electricaltrench and is pivotal about a pivotal axis extending between the groundengaging elements. The device includes one or more magnet means whichare spaced from the ground engaging elements and remote from the pivotalaxis. The cover plate is moved relative to the electrical trench byenergizing the magnet means to retain the cover plate by magneticattraction and pivoting the device about the pivotal axis with the coverplate thus retained.

This invention relates to apparatus for raising and lowering coverplates, and more particularly to apparatus for raising and loweringsteel cover plates associated with electrical trenches and withoutmarring a decorative coating applied to the cover plates and thesurrounding floor.

Electrical trench assemblies provide an electrical conductor carryingchannel of great capacity. See US. Patent Nos. 3,262,238 and 3,237,356.Accessibility to the interior of the trench assembly is essential toaccommodate frequent alterations in the use of electrical energy.Accordingly, all trench assemblies are provided with removable coverplates. Also in modern building floor constructions, a decorativecoating is normally applied over the exposed floor surface, for example,linoleum, asphalt tile, rubber tile, ceramic tile and the like. Thedecorative coating is also applied over the cover plates of the trenchassemblies to blend the cover plates with the remaining floor area.

The cover plates normally comprise heavy steel plates which are capableof supporting relatively heavy loads as well as personnel trafiic. Forexample, cover plates onequarter inch thick, eighteen inches wide andthree feet long are common. The cover plates are quite heavy, ranging inweight from 45 to 60 pounds, and are relatively difiicult to handle whenremoved or replaced in the trench assemblies. To further aggravate theproblem, the cover plates are normally installed in the trenchassemblies in end-to-end abutting relation, that is, with little or nospace between adjacent cover plates. The cover plates have been removedby inserting a tool, such as a screwdriver, between adjoining coverplates, prying up that plate which is to be removed and sliding it overadjacent floor covering materials.

As should be evident, the decorative coating edges and surfaces ofadjoining cover plates are prone to damage, as by cracking, gouging andthe like. The surrounding floor tile also is damaged by customaryhandling procedures-most damage occurring during removal or replacementof the cover plates.

OBJECTS Accordingly, as an overall object, the present invention seeksto provide a portable device for raising and lowering steel cover platesfrom electrical trenches without damaging the decorative coatingprovided on the cover plates.

Another object of the present invention is to provide a portable deviceemploying magnet means for attracting and retaining the cover plateswhile they are raised and lowered relative to the trench assembly,whereby no damage occurs to the decorative coating.

A further object of the present invention is to provide a portabledevice by which raising and lowering of heavy steel cover plates isaccomplished in a rapid and relatively easy manner.

STATEMENT OF INVENTION In accordance with the present invention, aportable device is provided for raising and lowering steel cover platesfrom electrical trenches without damaging the decorative coating appliedto the steel cover plates. The portable device comprises a frameincluding a carrier arm and a handle angularly extended from the carrierarm. A pair of ground engaging elements such as wheels is connected tothe frame and positioned to straddle the electrical trench. Anelectromagnet is mounted on the carrier arm at a position spaced fromthe ground engaging elements. Means for energizing and deenergizing theelectromagnet when desired is also provided. The overall arrangement issuch that the frame may be pivoted or rocked about the ground engagingelements whereby the electromagnet is lowered into engagement with thecover plate to magnetically attract and hold the same and then raisedthereby lifting the cover plate from the electrical trench. Replacementof the cover plate is accomplished by reversing the above-describedoperation.

In accordance with the preferred embodiment of the present invention,the ground engaging elements and the electromagnet are positioned atopposite ends of the carrier arm and spaced apart by a distancesubstantially equal to the length of the cover plate. With thisarrangement, the electromagnet attracts one end of the cover plate andwhen the electromagnet is raised, the cover plate is tilted about itsopposite end which is adjacent to the ground engaging elements. Completeremoval of the cover plate may now be accomplished with little chance ofdamaging the decorative coating.

In accordance with an alternative embodiment of the present invention,the ground engaging elements are positioned at a central location on thecarrier arm. Two electromagnets are employed, one positioned at each endof the carrier arm. The overall arrangement is such that the frame maybe rocked about the ground engaging elements to lower one of theelectromagnets into engagement with the cover plate to magneticallyattract and hold a first end thereof and then pivoted in the oppositedirection to lower the second electromagnet into engagement with theopposite end of the cover plate to magnetically attract and hold thesame. Rotation of the carrier arm into a horizontal position causes thecover plate to be raised, in its entirety, for transport to anotherlocation.

The above and other objects and advantages of the present invention willbecome apparent from the following detailed description by reference tothe accompanying drawings, in which:

FIGURE 1 is a fragmentary isometric view of a building floorincorporating an electrical trench and illustrating the use of thepresent portable device;

FIG. 2 is a cross-sectional view taken subtsantially along the lineII-II of FIG. 1, illustrating the initial position of the presentportable device;

FIG. 3 is a cross-sectional view taken along the line HII'II of FIG. 2;

FIGS. 4 and 5 are cross-sectional views, similar to FIG. 2, illustratingsuccessive steps employed in raising or lowering the cover plate; and

FIGS. 6 and 7 are side views schematically illustrating alternativeembodiments of the present portable device.

Referring now to FIG. 1, there is illustrated a building floor structure10 comprising a cellular metal subfloor 12 providing a plurality ofelectrical raceways 14; an electrical trench 16 disposed above thecellular metal subfloor 12; and a layer of concrete 18 poured over thecellular metal subfloor 12 and about the electrical trench 16. Althoughnot shown, the electrical trench 16 communicates with certain of theelectrical raceways 14 and cooperates therewith to distribute the powerand communication cables throughout the floor area. A decorative coating20, such as linoleum, asphalt tile, rubber tile, ceramic tile and thelike, is applied over the layer of concrete 18.

The electrical trench 16 provides an electrical conductor carryingchannel 22 of great capacity. The electrical trench 16 includes aplurality of removable cover plates 24 which overlie the channel 22 andare positioned in end-to-end abutting relation. The decorative coating20 is also applied to the cover plates 24 so as to blend the coverplates 24 with the remaining floor area. Because the cover plates 24 arepositioned in end-to-end abutting relation, it is difficult to removethe cover plates 24 without marring the decorative coating 20.

Referring now to FIGS. 1, 2 and 3, there is illustrated a portabledevice 26 shown positioned over the electrical trench 16 preparatory toraising one of the cover plates 24. The portable device 26 comprises aframe 28 including a carrier arm 30 and a handle 32 angularly extendedfrom the carrier arm 30. A pair of ground engaging'elements preferablycomprising wheels 34, is connected to the frame 28 and positioned tostraddle the electrical trench 16. An electromagnet 36 is mounted on thecarrier arm 30 and is spaced from the wheels 34. The electromagnet 36 ispivotally mounted on rod elements 38 extended from the carrier arm 30,for free pivotal movement about a horizontal axis indicated by the dashdot line 40 (FIG. 3). In this manner, the lower or active face 42 of theelectromagnet 36 will normally be horizontally oriented and ready toenter a flush engagement with a cover plate.

A grip 44 is provided on the handle 32 and has a power cord 46 extendingtherefrom to a power source which supplies electrical energy to theelectromagnet 36. Switch means 48 may be incorporated into the grip 44to energize and deenergize the electromagnet 36.

As can best be seen in FIG. 2, the present portable device 26 ispositioned to straddle the electrical trench 16 and is pivotal about thewheels 34. To remove one of the cover plates 24, the handle 32 is pushedforwardly so as to lower the electromagnet 36 into engagement with asubjacent cover plate 24A, as shown in FIG. 4. Thereafter, the handle 32is pivoted toward the trench 16 so as to raise the electromagnet 36 andthe subjacent cover plate 24A attracted thereto. Thereafter, thesubjacent cover plate 24A may be removed manually to a differentlocation on the floor area.

It is to be noted at this time that only the electromagnet 36 comes intodirect contact with the decorative coating 20. Inasmuch as the frame 28is rollably supported by the wheels 34 and since the electromagnet 36 ispivotally mounted, raising or lowering of the subjacent cover plate 24Ais accomplished with no relative motion occurring between theelectromagnet 36 and the subjacent cover plate 24. Consequently, theelectromagnet 36 does not mar the decorative coating 20. Furthermore,since the electromagnet 36 attracts one end of the subjacent cover plate24A and tilts the same about its opposite end, the electromagnet 36 isrequired to support less than the total weight of the cover plate 24A.

In order to replace a cover plate which has been removed, the coverplate 24A is initially positioned as shown in FIG. with the energizedelectromagnet 36 engaged therewith. Thereafter, the handle 32 is pushedforwardly thereby lowering the cover plate 24A into a properly seatedrelation with respect to the adjacent cover plates 24B as illustrated inFIG. 2. The electromagnet 36 is then deenergized and raised, as shown inFIG. 2, and the portable device 26 is then moved. Again, there is norelative movement between the electromagnet 36 and the cover plate 24and, consequently, the decorative coating 20 is not marred.

The present invention also provides a novel method for raising andlowering the steel cover plates without marring the decorative coating20. As can be seen in FIGS. 2, 4 and 5, the cover plates are positionedin end-toend closely adjacent relation in the electrical trench 16. Forexample, the subjacent cover plate 24B and the decorative coating 20thereof present opposite end edges 50A, 52A which are closely adjacentto opposite end edges 50B, 52B, respectively, of the adjacent coverplate 24B.

In practicing the method of the present invention, an end region 54 ofthe subjacent cover plate 24A, for example, is attracted by permeatingthe same with magnetic flux radiating from the magnet means 36 engagedtherewith. Thereafter the magnet means 36 and the end region 54 aremoved as a unit to effect tilting of the subjacent cover plate 24A aboutits opposite end 52A and relative to the electrical trench 16. The endedge 50A is moved substantially perpendicular relative to the end edge52B of the adjacent cover plate 24B whereby the decorative coatings 20of the subjacent cover plate 24A and of the adjacent cover plates 24Bare unharmed.

ALTERNATIVE EMBODIMENTS Two alternative embodiments of the presentportable device will now be described with reference to FIGS. 6 and 7.Corresponding numerals will be employed to identify corresponding partsheretofore described.

Referring in particular to FIG. 6, there is illustrated a portabledevice 26' wherein the electromagnet 36 is pivotally supported adjacentto the handle 32 while the wheels 34 are carried at the opposite end ofthe carrier arm 30. Operation of the portable device 26 corresponds tothe operation of the portable device 26, as described above.

Referring now to FIG. 7 there is illustrated a portable device 56wherein the wheels 34 are mounted at a central location on the carrierarm 30. A pair of electromagnets 58, 60 is pivotally mounted at theopposite ends of the carrier arm 30. In this embodiment, the arrangementis such that the frame 28 may be rocked about the wheels 34 such thatfirst the electromagnet 58 is lowered into engagement with the subjacentcover plate 240 and to magnetically attract one end thereof, andthereafter rocked in the opposite direction about the wheels 34 suchthat the second electromagnet 60 is lowered into engagement with theopposite end of the subjacent cover plate 240. Thereafter, the carrierarm 30 is positioned horizontally and the subjacent cover plate 240 isremoved from the trench 16 and is vertically spaced therefrom. Theportable device 56 may now be rolled away to transport the subjacentcover plate 24C to a different location. It should be evident that byreversing the above-described procedure, the subjacent cover plate 24Cmay be replaced in the electrical trench 16.

SUMMARY The present invention provides a portable device which raises orlowers heavy steel cover plates from electrical trenches withoutdamaging the decorative coating provided on the cover plates.Furthermore, means in the form of a portable device, is provided bywhich the raising or lowering of heavy steel cover plates isaccomplished in a rapid and relatively easy manner. Also, the presentinvention provides a novel method for raising and lowering heavy steelcover plates which substantially completely eliminates the chance ofdamaging the decorative coating.

I claim as my invention: 1. The combination of a steel cover plate of anelectrical trench and a portable device for raising and lowering saidsteel cover plate wherein said device comprises:

a [frame including a carrier arm and a handle angularly extended fromsaid carrier arm;

a pair of ground engaging elements connected to said carrier arm andpositioned to straddle said steel cover plate;

said frame being pivotal about a pivotal axis extending between saidground engaging elements;

magnet means mounted on said carrier arm at a position spaced from saidground engaging elements and remote from said pivotal axis; and

means for energizing and deenergizing said magnet means when desired;

whereby said cover plate may be moved relative to said electrical trench.by energizing said magnet means to retain said cover plate by magneticattraction and by pivoting said device about said pivotal axis with saidcover plate thus retained.

2. The portable device as defined in claim 1 wherein said magnet meansis pivotally mounted on said carrier arm whereby a lower face of saidmagnet means is positioned for fiush engagement with said cover plate.

3. The portable device as defined in claim 1 including:

second magnet means mounted on said carrier arm at a position spacedfrom the first said magnet means and remote from said pivotal axis; and

means for energizing and deenergizing said second magnet means whendesired;

the first said magnet means and said second magnet means cooperating tolift a said cover plate in its entirety from said electrical trench andfor transport away from said electrical trench.

4. The portable device as defined in claim 3 wherein said groundengaging elements are positioned intermediate of the first said magnetmeans and said second magnet means.

5. The device of claim 1 wherein the said handle connects to saidcarrier arm at the rear end of said carrier arm;

said ground engaging elements are connected to said carrier arm adjacentto said rear end; and

said magnet means is connected to said carrier arm adjacent to theforward end of said carrier arm.

6. The device of claim 1 wherein said handle connects to said carrierarm at the rear end of said carrier arm;

said ground engaging elements are connected to said carrier arm adjacentto the forward end of said carrier arm; and

said magnet means is connected to said carrier arm adjacent to said rearend of said carrier arm.

7. The device of claim 4 wherein the first said magnet means and saidsecond magnet means are pivotally mounted on said carrier arm whereby alower face of the first said magnet means and a lower'face of saidsecond magnet means are positioned for flush engagement with said coverplate.

References Cited UNITED STATES PATENTS 710,041 9/ 1902 Clark 294 .51,539,891 6/1925 Wood 294-65.5 X 2,379,596 7/ 1945 Seamans 294-65 .52,952,373 9/1960 Bie 214-375 FOREIGN PATENTS 311,343 7/1917 Ger-many.

ALBERT I. MAKAY, Primary Examiner.

US. Cl. X.R. 214-384; 254-8, 131; 294-655

